• Energy Research

AbstractAn artificial neural network (ANN) and a genetic algorithm (GA) are employed to model and optimize cell parameters to improve the performance of singular, intermediate‐temperature, solid oxide fuel cells (IT‐SOFCs). The ANN model uses a feed‐forward neural network with an error back‐propagation algorithm. The ANN is trained using experimental data as a black‐box without using physical models. The developed model is able to predict the performance of the SOFC. An optimization algorithm is utilized to select the optimal SOFC parameters. The optimal values of four cell parameters (anode support thickness, anode support porosity, electrolyte thickness, and functional layer cathode thickness) are determined by using the GA under different conditions. The results show that these optimum cell parameters deliver the highest maximum power density under different constraints on the anode support thickness, porosity, and electrolyte thickness.

Abstract Utilizing oxygen with methane as fuel is a feasible reforming strategy, more convenient and less costly in terms of configuration in solid oxide fuel cells (SOFC) systems. Current study addresses the issues related to the favorable operating conditions for the internal catalytic partial oxidation (CPOX) reforming of methane over Ni-YSZ cermet anode of SOFCs with a new analytical approach on the basis of Reynolds number (Re). The effect of the different flow rates of methane-oxygen mixed gas on the performances of SOFC are studied in fixed methane to oxygen ratio. The results indicated that the peak of power density (PPD) strongly depends upon the Reynolds number at the fuel channel inlet that controls the mixture of methane and air mass flow rate. The maximum value of PPD is obtained in Reynolds 10 and also the PPD is decreased by increasing Re. The electrochemical experiment showed stable performance of the SOFC in this condition and confirmed its durability after 120 h testing. The electron microscopy demonstrated that there is no trace of carbon in the anode which led to the durability of the SOFCs.

Abstract The suitable ratio of methane to oxygen is a critical selection to optimize the solid oxide fuel cells performance under internal catalytic partial oxidation reforming. In the current study, a design of experiment (DOE) with the full factorial analysis was employed to determine the optimum peak power density (PPD) as the objective function based on the flow rates as the decision variables. The response surfaces of PPD and its contour were presented in terms of the levels of the methane and oxygen flow rates. However, the low flow rate ratio of O2 to CH4 maximizes the PPD, the high risk of carbon deposition is occurred. The optimum PPD value was determined through the superposition of contour plots for regions with Reynolds (Re) number of fluid flow around 10 and O2/CH4 ratios among 0.2–0.4. The electrochemical experiment testing illustrated a stable performance of the SOFC in the optimum condition of the fuel flow rate after 120 h testing time. Furthermore, the scanning electron microscopy revealed no visible trace of carbon and crack on the anodic surface of the cell.

The use of natural gas as fuel for solid oxide fuel cell is one of main potentials of this technology to be exploited as an efficient and profitable future power generation source. However, using direct methane (main component of natural gas) in conventional nickel-based fuel cells leads to carbon deposition problem which causes performance failure even in short period (24 h). According to thermodynamic principles, fuel addition with oxygen carriers is a good solution to prevent carbon deposition problem. Among the different options, a deep investigation is here presented for the air addition case. Through experimental activity under different operating conditions and suitable performance and structural cell characterization, the 1:5 optimal air addition to methane is determined, providing outcomes of interest for SOFC operation optimization in case of direct methane feeding. In fact, through impedance spectroscopy analysis and voltage measurements, as well as ex-post structural analysis, it is proved that in these conditions both carbon deposition and anode layers delamination are avoided, also after 100 h operation; moreover a cell stable operation at 0.6 V is guaranteed. The proposed operation mode, therefore, represents a promising solution, to be deeply investigated in the future at stack level, for SOFCs directly fed with natural gas.

In this paper, a mode of nanostructured Pd anode of SOFCs is presented to calculate the effects of nanoparticles on the SOFCs' electrodes performance. Nanostructured electrodes of the SOFCs prepared by wet impregnation have attracted increasing attention as the most effective way to make highly active and advanced structures in the electrodes. The effects of infiltrated Pd-nanoparticles on the performance of Nickel/ Gadolinium doped Ceria (Ni/GDC) anode of SOFC are investigated. It is observed that a small amount of Pd catalyst has a significant decreasing effect on overpotential of anodes. One-dimensional analysis is carried out using a simplified geometry to calculate the effective polarization resistance by assuming the ionic conductor phase (GDC) as columns and the Pd phase mounted on these columns. The results of modeling are presented and compared with the experimental data as a function of temperature.